1. Field
This invention relates to exercise machines, and more particularly to stepper exercise machines.
2. State of the Art
Steppers and climbers all have a pair of foot pedals or treadles with a resistance connected to resist stepping movements. Typical machines are synchronized so that as one pedal or treadle is pushed downward by the user's foot, the other one rises upward. An essential aspect of a stepper, then, is a means to synchronize the reciprocating action of the foot bars.
U.S. Pat. No. 4,600,187 (Schenker) discloses a step exerciser with a rocker plate having holes at the opposing ends through which pass the left and right step arms. Schenker does not compensate for either the arcuate travel of the ends of the rocker plate in their plane of vertical travel, or the analogous arcuate travel of the step arms in their plane of travel. The result is that the step arms will shift back and forth in the holes of the rocker arm, which may cause rough and noisy action and substantial wear on the parts.
A rocker is also employed in the apparatus disclosed in U.S. Pat. No. 4,830,362 (Bull). In this case, the foot levers are connected via tie rods to the rocker ends. In the Bull apparatus, the arcuate travel of the levers is compensated for by pivots at the points connecting the tie rods to the rocker ends and the foot bars. The linkage arrangement is complex, relatively easily damaged by improper assembly, and subject to frictional wear at all of the pivot points.
A third rocker-type reciprocator is found in an exercise machine marketed by Voit and shown in FIGS. 5 and 6. In this assembly, the arcuate travel of the levers is accommodated by having the ends of a rocker bar slide on rollers attached to the underside of each lever. However, the arrangement requires capturing the rocker bar on the rollers. This arrangement is complicated, requiring accurate alignment and narrow construction tolerances, and is therefore difficult to manufacture.
A simplified rocker reciprocator for a stepper machine which has smooth, quiet action with a minimum of parts subject to friction is needed. Also, a reciprocator which can be easily assembled from a compact disassembled state by a home user is needed.